Light scattering by monodisperse solutions of rigid rod-like anisotropic macromolecules, with linear dimensions l of the order of incident wavelength λ, oriented in an external d.c. electric field, → E has been analysed. The relative variations δV E v , δH E v , δV E h , δH E h of the scattered light components are discussed for the three values [ l λ ] = 1, 0·5, 2 , and various reorientation parameters, p = [ μ E kT ] of the permanent dipole moment μ and q = [( α 3 − α 1) E 2/2 kT] of the moment induced by the principal polarizabilities α 1 = α 2 ≠ α 3. The saturation orientation field strength has been calculated for certain macromolecules with the aim of determining their optical anisotropy numerically.